This invention relates to weed control in large seeded crops and certain medium and small seeded crops via the application of certain 5-amino-3-oxo-2-phenyl-4-(3-trifluoromethylphenyl)-4,5-dihydrofuran derivatives.
U.S. Pat. No. 4,568,375 discloses a genus of herbicidal compounds having the formula: ##STR1## wherein R is alkyl, cycloalkyl, alkenyl, haloalkyl, haloalkenyl, alkoxyalkyl, alkylthioalkyl phenyl, naphth-1-yl, inden-1-yl, substituted aryl or optionally substituted aryl; R.sup.1 is hydrogen or alkyl; R.sup.2 is hydrogen, alkyl, alkenyl, alkoxycarbonylalkyl, alkoxylalkyl, alkylthioalkyl or R.sup.1 and R.sup.2 together with the nitrogen atom to which they are joined form a heterocycle; X is hydrogen, alkyl, alkoxyl halo or trifluoromethyl and Y is alkyl, alkoxyl halo, haloalkyl, haloalkoxy or haloalkylthio with certain provisos excluding certain compounds.
This patent teaches that such compounds have both preemergent and postemergent activity and have especially good preemergent activity against a broad spectrum of broadleaf and grassy weeds. The patent further teaches that compounds wherein R is phenyl, methylphenyl, halophenyl, methyl, ethyl, or propyl; and/or one of R.sup.1 or R.sup.2 is hydrogen and the other is methyl; and/or X is hydrogen and Y is 3-trifluoromethyl are especially preferred. The patent presents Tables of biological data showing high preemergent phytotoxicity for a number of the preferred compounds with respect a variety of weeds and also with respect to soybean and rice.
U.S. Pat. No. 4,596,595 discloses herbicidal compounds having the formula: ##STR2## wherein n is 0, 1, or 2; R is alkyl, cycloalkyl, (cycloalkyl)alkylene, alkenyl, haloalkyl, haloalkenyl, alkoxy, alkylthio, alkoxyalkyl, alkylthioalkyl, or certain optionally substituted aryls; R.sup.1 is hydrogen or alkyl; R.sup.2 is hydrogen, alkyl alkenyl, alkoxycarbonylalkyl, alkoxyalkyl, or alkylthioalkyl; or R.sup.1 and R.sup.2 together with the nitrogen to which they are joined form a nitrogen heterocycle; X is hydrogen, alkyl, alkoxy, halo, or trifluoromethyl; and Y is alkyl; alkoxy; halo; haloalkyl, haloalkoxy, with provisos excluding certain compounds.
This patent teaches that such compounds exhibit both preemergent and postemergent herbicidal activity and especially good preemergent activity. The patent further teaches that by varying the dosage rate, certain of the compounds exhibit acceptable safety with respect to certain broadleaf crops, notably soybean crops, while retaining a broad spectrum of preemergent herbicidal activity against both broadleaf weeds and grasses.